Page 56 - Engineering in Nature

Engineering in Nature

The back fur being thicker than that on the stomach means that the
koala can collect the heat from the sun and insulate itself. Although
the stomach hairs are sparse, the animal can regulate the decree of in-
sulation by causing these hairs to stand on end.

On windy days, the koalas in the trees simply turn their backs to
the wind as it gains in intensity. More and more, they transform into
something resembling a soft, furry ball. As the wind blows harder
they also turn their ears forward, so that no open areas are exposed.
The wind has little effect on this thick, mattress-like back fur, so that
when the wind blows hard, the body can maintain its temperature
unchanged. Even on cold days and in strong winds, the reduction in
the fur's heat retention capacity is less than 14%. Even in the strongest
winds, fur provides perfect heat retention for a tree-dwelling animal.
The koala also regulates the speed of its metabolism to compli-
ment the heat regulation its fur performs. The koala's metabolism is
rather slow—only 74% of that of other placental animals, and one of
the reasons why the animal experiences a low level of water loss. 17
To recapitulate the features possessed by koalas:
Their body structure lets them climb trees and live there comforta-
bly.
The special structure of their digestive systems let them obtain suf-
ficient food and water from the plentiful eucalyptus leaves on the

trees where they live.
Their physiological system eliminates the poisonous effects of the
oils in the leaves.
They use certain eucalyptus leaves as drugs to rectify various im-
balances in their bodies.
Their physiologies let them make maximum use of the the leaves'
water content.

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